Identification of T-cell epitopes using allele-specific ligand motifs.

In order to facilitate the identification of T-cell epitopes as useful components of synthetic vaccines, we investigated the role of MHC molecules as the restriction element for the recognition of epitopes by the alpha beta receptor of T cells. MHC molecules are able to present thousands of different peptides to T cells, with all the peptides presented by one distinct type of MHC sharing common structural features. Our group analyzed these common characteristics concerning peptide length (only MHC I ligands) and anchor positions (MHC I and II ligands) occupied by a small set of closely related amino acids. Until now, for more than fifty MHC proteins allele-specific "peptide motifs" have been defined. The exact knowledge of MHC I peptide motifs allows for a prediction of CTL epitopes, and this kind of prediction has been successful in many cases over the last three years.